Telephone-exchange system.



E. E. CLEMENT.

- TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 18, 1912.

I Patented Oct 10, 1916.

4 SHEETS-SHEET 1 E. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE UL 1912.

Patented -0ct.10,1916

4 SHEETS-SHEET 2.

E. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM. APPLICATION HLEVD JUNE 18, 1912.

' Patented Oct. 10, 1916.

4 SHEETS-SHEET 3.

10 NW a n W 4 SHEETS-SHEET 4- Patented Oct. 10,1916.

E.. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE I8, 912.

aMLUMO'D irnn snares earner orrrcn.

EDVTARD E. CLEMENT, OF WASHINGTON, DISTRIQT OF COLUMBIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO JAMES B. GARFIELD, TRUSTEE, F CLEVELAND, OHIO,

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Got. 10, 1916.

Application filed June 18, 1912. Serial No. 764,326.

To all whom it may concern:

Be it known that I, EDWARD E. CLEMENT, a citizen of the United States, residing at Vashington, in the District of Columbia, have invented certain new and useful 11nprovement in Telephone-Exchange Systems, of which the following is a specification,

' reference being had therein to the accompanying drawing.

My invention relates to telephone GX change systems, and particularly to semiautomatic systems in which the interconnection of subscribers for conversation is eflected by means of automatic switches controlled by operators located at a central oflice, in response to oral instructions re ceived from the calling subscribers.

The object of the present invention is to give the calling subscribers direct access to the operators, without going through any portion of the switches or trunks used for interconnections. For this purpose, I provide a certain number of auxiliary switches which I call primary selectors, whose function is to automatically connect with calling lines in response to the subscribers acts in calling; a number of associated auxiliary switches which I call secondary selectors, whose function is to select the idle operators and connect the primary selectors therewith; a number of auxiliary switches associated with the operators positions, which I call distributing switches, whose function is to connect the operators with idle connective trunks and switches; and. finally the usual complement of automatic selector switches commonly employed in any such systems as for example the Strowgenavhich receive impulses from the operators through the distributing switches, after the oper atorshave communicated with the calling subscribers through the primary and secondary switches.

A characteristic feature of the system is this, that the automatic connective switches are all worked by definite impulses trans mitted from the operators keys and sending machine, so that the number of the calling subscriber being first known to the operator, she sends the proper impulses to step up the connective switches on one end to the calling line contacts, and on the other end to the called line contacts. Thus, the calling and called parties are both connected simultaneously to the connective switching trunks, which are brought into service at the moment of use only, and are never idle during the period between the call and the completion of the connection. In systems heretofore proposed, one portion of the connec tive trunks has become connected with a calling line in response to a call, and remams so connected until the operator could obtain the number and complete the connection. Bythe present arrangement I increase the efiiciency of the connective trunks and switches, and efi'ect'a more perfect distribution of calling lines among all the operators.

A number of subsidiary features of the invention and advantages flowing therefrom will appear from the detail description.

My inventionis illustrated in the accompanying drawings in which- Figure 1 is a diagram of a subscribcrs line, a central ofiice connector containing terminals of this and other lines, and a primary switch also containing terminals of the same lines, with its associated secondary switch containing terminals of the operators circuits. Fig. 2 is a diagram constituting a continuation of Fig. l, and showing a permanently connected pair of first selectors, with a pair of associated second selectors through which connection may be established between the connectors of Figs. 1 and 4-. Fig. 3 is a diagram constituting a continuation of Fig. 2 and showing an. operators position, with primary and secondary distributing switches to connect the operator to the central switching trunks of'Fig. 2, also a portion of-the wiring extending to the secondary selector switch of Fig. 1. Fig. 4; is a diagram constituting a further continuation of Fig. 2, and showing a connector and line circuit, similar 'to those of Fig. 1, but without the primary and seccally through the switches S and S of Fig. l to the operators position in Fig. 3. The operator ascertains boththe number of subscriber A and the number of the subscriber wanted, who for purposes of description'we will assume to be subscriber A in Fig. 4. The operator sets up these two numbers on the two sets of'keys at K and K respectively, and impulsesare then directed from the sending machine D through the keys which have been depressed by way of the wires 67-68 and 167168 and the switches S S 'to the first selector switches S and S respectively in Fig. 2. The impulses from the keys K to the switch S cause selection through the switches S, Sf--of the calling line; and the impulses from keys K to the switch S cause selection through the switches S and S of the wanted line. A circuit for conversation is thus established extending from A in Fig. 1 through the switches of Figs. 1,2 and 4 to the station A in Fig. 4, and thereupon the operators switches S and S become automatically disconnected, leaving the conversationcircuit under the exclusive control of the connected subscribers. As soon as the operator has set up the numbers, and depressed her,

starting key K her work on this connection is finished, and the primary and secondary switches S and S are automatically released, ready to pick 'up another calling line and another operators position. Each operator can be provided with more than one of the double sets of keys shown in Fig. 3, so as to increase her capacity for answering calls. The description herein will be limited, however, for convenience, to the single equipment shownin Fig. 3.

The switches S S*, S-S ,-in

Figs. 2, l and 4 respectively, are shown of the well known Strowger type, which require no detailed description. The two switches S and S in Fig. 2 are both what are known as first selectors, each adapted to select an idle trunk in a desired thousands group. These two switches are permanently connected through the condensers C and C, the switch S always being used to find the calling line while the switch s is always used to find the wantedline. These are the only switches thus limited in their functions however, since the second selectors TS and S and the connectors S and S are employed indiscriminately in the selection of both calling and wanted lines. An economy is hereby effected, because each line, instead of hav- .ing multiples, such as -c"'-c" and (r -0 in two different classes of switches, now has multi les in only one class, viz., the connectors S. Since these connectors are available for-either calling in or calling out, a smaller num cr'will sufiice, probably not more than 15 per cent. of the number of lines in general. The same is true of the second selectors, which contain the terminals c 0 c, 0 c c of the connector switches and which may be reduced proportionately. The number of multiples c 0 c c "-c 0 representing the second selectors in the banks of the first selectors S and S will be greater than in the ordinary system's, because the second selectors would be accessible in both directions, that is to say from'both classes of first selector switches. As the percentage of second selectors is reduced however, this need not unduly increase or change the trunk provision in the first selectors.

The primary and secondary switches S and S require some description. These are electrically connected in pairs, and are power .driven, having rotary motion only, and always traveling in the same direction. F or convenience I have shown one pair of these switches mounted so as to be driven by a common shaft 8, carrying a pulley 8' connected to a source of power through a belt .9 contacts of which only those onone side are shown,at 0 c c ,c

The switch S comprises a bank of w?, which are carried by but insulated from. v

a metal sleeve 8 surrounding the spindle 8. At the upper end of this sleeve I provide a sliding collar 8 splined or feathered to the sleeve so as toturn with it, this collar being one element of a clutch of which the other element 8* is fixed rigidly on,the spindle .9. The element 8 has a finger projecting on one side, and the collar 8 has a corresponding finger projecting outwardly and upwardly from its body so that when it has slid up in the position shown in Fig. l, the

structure and arrangeme t to the switch S,

with the single exception that its clutch is engaged when its controlling magnet M is energized, and disengaged at all other times. The reason for this difference is that the switch S is constantly rotating in order to sweep its wipers over the line contacts, whereas the switch Sis normally at rest with its wipers touching the contacts of an idle operators circuit.

As soon as the operator has obtained the numbers of the lines calling and wanted, and having set them up, press'es her starting key K, a circuit is closed for the relay R in Fig.

1, which becoming energlzed closes the circuit of the clutch magnet M, which in turn raises the clutch member s to engage the spindle member s, to thereby rotate the sleeve 8 and carry the wipers w'w w -wf-w ofi' the contacts of the operator in question. Moreover, it will be observed that the relay R is self-locking, and

' of the operators key set being engaged inafter .once becoming energized in this manner 1t Wlll remain energized, so as to keep the-sleeve s rotating, as long as the wiper w is passing over contacts 0 appertaining to operators who are busy. 'Each operators key set has a busy relay R", for this purpose, and as will hereafter appear, so long as this relay is energized by reason transmitting a call, so long will the bat tery be connected to the contacts 0 in all the secondary switches S, through wire 43. Thus the switch S when released, will continue its movement until an idle operator is reached and will then come to rest; and conversely as soon as the operators key set is again free, its relay R will become denergized and any of the switches S may again come to rest on her contacts.

The bank of each primary switch S may conveniently contain the multiple contacts of 100. lines, and the bank of each secondary switch S may contain multiple contacts for all the operators in the exchange.

there should be at least as many pairs of switches SS' as there are groups of 100- subscribers each; and should traflic conditions render it desirable or necessary, there may be two, three or more pairs of switches S-S for each group of subscribers. The actual number depends upon the number of simultaneous calls to be provided for in any particular grou'p,and under ordinary traflic conditions, this would rarely exceed five and would commonly be no more than three. Each group of subscribers thus has access through each of its pairs of primary and secondary switches S--S to all of the operators, and therefore any line in the exchange may become connected when calling to any operator. In this particular my row shown on the right of the key set K by which the selective ringing generator is connected for party line signaling, which however has nothing to do with the present invention.

The several keys in each of these Thus,

sets are connected so as to derive their impulses from one to ten, from the several spring contacts resting on the drum D which is supposed'to be constantly rotated by a suitable motor as shown. The drum carries-four sets of teeth, so as to send impulses from one to ten four times in succession, and each strip of keys in the set K or K is cut on in succession, by means of suitable relays or switches so as to prevent confusion in transmission. At the end of each rotation of the machine, that is to say at the end of a complete cycle of impulses, the spiing 136 is closed to ground by wire 135 which is connected to the various keysets and through each to the wire 71 and the relay R Thus after the full number is transmitted, the relay R is automatically energized, to deenergize and release the busy relay R, whichfin turn restores the ground to the relay R for the purpose of energizing that relay through the wire 46, the wipers w and 0 etc, and causing the switch S to step off the multiple contacts of the trunk switch S so as to disconnect the operator, which of course is necessary after the connection is thus completed.

The switches S 1 call the primary distributing switches. Each has a spindle driven step by step by means of an electromagnet M which is normally energized by impulses from a commutator I whenever the relay R is active. This relay depends for its current upon a circuit from battery through the wire 141 and wiper 10 which. wiper is moved around by the spindle to test,

'contacts'c f connected to the several trunks in Fig. 2. The contacts 0 0 and 0 are. not multipled, but each trunk has one set of these contacts in one only of the switches S Thus, in a 10,000 line exchange, assuming 1000 trunks, 50 switches S with 20 con-' tacts each, or 20 switches with 50 contacts each, would sulfice to give access to all of the trunks. Each of the switches S is represented by multiple contacts 0 -c"-0 in the banks of eachof the operators secondary distributing switches S Assuming 25 operators, each with two key sets, and" each key set provided with a switch S there would be a total of 5 0 switches S3, each containing a multiple contact for each of the switches S, so there would be 50 multiples connected.

to each of the wires in'the set leading from switch S The switch S as hereafter appears, will always reston the coi tacts of an idle trunk shown in Fig.2, and the switch S will always seek and rest upon the contacts of a switch S which is 'thus resting on the contacts of an idle trunk. It will be observed that by the use of these primary and secondary distributing switches, any

operator in the entire exchange can have access to any one of the trunks in the exchange, so that as amatter of fact', any subscriber may reach any operator, and may be connected through any pair of selectors in the entire exchange, which gives the widest' distribution of load, the highest efliciency inthe apparatus, the lowest percentage of apparatus and wiring required, and the lowest cost of maintenance.

- gizes the relay R, the energizing current be5 The detail features of invention it is thought will sufficiently appear from the following distribution of operation. It is as-' sumed as already stated, that subscriber A in Fig. 1 calls by taking down his receiver.

\Vhen the subscriber A takes down his receiver the line circuit 1-2 is closed and his line relayR is energized by currentover the following path: battery lead 21, R, 22, 1*,

line wire '1, through subscribers telephone apparatus, linewire 2, a 23, and ground. Thereupon the armatures r, r and r of relay R pull up.

selectors through the following path: battery lead 21, 1", 24, 25,0 The wiper 40 of the primary selector switch S coming into engagement with, the contact 0 enering from battery to the wiper o as above traced and thence through wiper w, 26, R, 27,7 to ground. The relay R attracts its armatures completing the circuit ofits holding winding, from battery lead 28, 9' 29, R, 30, 27,1 to ground and at the'same time energizes the clutch magnet -M'by cur- .rent from battery lead 31, M,. 32, r, to

ground. The magnet M attracts its armature throwing down the clutch lever 2 .which disengages the lower clutch member s from the upper rotating member s", and brings it down .onto the loose wiper sleeve 8 the ,friction between the lever 2 and clutch memher .9 checking the motion of the sleeve and causing the wipers 10 w, w and w" to rest on their respective contacts 0 c, a

and 0. Simultaneously, the energizing circult of relay R is completed from battery" lead 35, R, 34, c t, 10*, 35", r" to ground,

and R attracts its armatures looking it through armature 1' 36, r to ground, and

disconnecting battery from themultiplecontacts e at 1" so that other primary selectorswho'se wipers 20 pass over the multiples 0 will not be affected... Simultaneously also with the actuation of the clutch magnet 'M the wiper w of the secondary selector switch S is grounded through the-following connections: to", 38,7 39, 1'. to ground,

and assuming that the wipers of the switch S are resting on the multiple contacts of an idle operators trunk, the operators line re-.

lay R, Fig. 3 is energized. by current from battery lead 36, R, 37, (37 Fig. 2, 37 Fig. 1) contact 0 wiper w to ground as above traced. The energization of relay R completes the circuit of the line lamp L through the armature 7' and the energizing circuit The armature 1" connects battery with the contact 0 of the primary of the operators busy 'relay RtFig. 3, the latter circuit being from battery lead 36. through 7-, 40, R, to ground, whereupon the relay R attracts its armatures, locking itself through 0*, 40, we, onto'battery lead 42, and connectsbattery onto the conductors 43v and 44 leading to the multiple contacts a and c on which rest the wipers of the. secondary selector switch S and pr mary distributing switch S respectively. The

former connection may be traced from bat-w tery lead 12 through 9', i3, (43 Fig. 2, 43 I Fig. 1) to c and the latter connection from battery lead 42 Fig. 3; through 1', 44, 1-

45. 46, -20 to 0*. The former circuit establishes a busy test which does not aflect the secondary selector S through which the call came as the circuit; of'tlie clutch relay R of. However any said switch is open at 1*. other secondary selector switches S that may be connected onto the multiples 0 immediately step around to the contacts of the next idle operator, their clutch relays R beingenergized by current from battery to the multiples 0 as above traced and thence -through w, 44, R 45, r to ground. The

relay R attracts its armatures, locking itself to ground and energizing the clutch magnetM' by current over the following path: battery lead 46, M, 17,1, to ground. The clutch magnet attracts its armature, throwing up the lever 2 which brings the clutch member 8 up into engagement with the constantly rotating member a, causing the wiper sleeve to rotate, and the test wiper' b 10 to sweep over the test contacts 0-.unt1lof" testing when the relay R is energized depriving its clutch relay R of one of its ground connections at 1', it would continue tov test as the relay R is locked onto ground through 7' and falls back only when the wiper w fails to find battery. Similarly the test on contacts a of switch S Fig. 3 does not affect the switch through which it originated as the circuit of the stepping relay R of that switch is opened at r as soon as R is energized, but any other primary distributing switches whose wipers 7w rest on the multiples of contact a will immediately begin testing for a contactrepresenting an idle secondary distributing switch as follows: The multiples of 0 being connected 'to battery as above described, current flows through the wiper 9c, 46, R, 48 7), to ground. The stepping relay .connects R in pulling up connects battery onto the stepping magnet M which is thereupon energized at each closure of the contact springs of the interrupter I, the circuit being from battery lead 42, 1", *9, M 50, 52, through the contact springs of the interrupter I and to ground.

The switch continues to step around until its wiper 10 engages a contact leading to an idle secondary distributing switch 5 (j. e. one which is connected through 137, R 138, r to ground) whereupon the relay B being deprived of its battery supply releases its armatures breaking the circuit of the stepping magnet M at 1' which causes the switch to come to rest with its wipers on. contacts leading to an idle secondary distributing switch S The completion of the busy. test as above described by the attraction of the armature r of relay R putting battery on multiples 0 causes the control relay R of the switch S to open the circuit of the stepping relay R at 2* which places the switch S under the control of the switch S, the energizing circuit of relay R being from battery to the contact 0" as previously traced and thence over wire137, through R, 138, 1' to ground.

Shoulda primary distributing switch be in the act of testing when its busy relay R is pulled up by a. calling subscriber it would continue to test, the circuit of its stepping relay R being locked to ground through 1' which circuit is broken only when the wiper w" engages the contact of an idle trunk which deprives the relay R of its battery supply.

, The operator seeing the line lamp L light up presses her listening key K Fig. 3 which energizes the relay R by current from battery lead 53, through the contacts of key K, 54, R to ground. The relay R pulling up locks itself onto battery through 7*, 55, 7;, 7c and battery lead 53, and at the same time the operators listening wires 5657 on to the calling subscribers line as follows: 56, r", 58, (58 Fig. 2, 58. Fig. 1) 0 10 59, 10 0 60, 0' 61, 1 substation A, line wire 2, 6 r", 63, 0 w, 64, w, c, 65, (65 Fig. 2, 65 Fig. 3) r; 57. The operator ascertains the number of the calling subscriber and the number of the subscriber wanted, sets up the two numbers on her key sets K and K respectively and depresses the starting key K which opens the contacts .lr-/l:, and closes the contacts 7;7c*". and Z;--k The opening of the contacts 71: breaks the locking circuit of the listening relay R which releases its armatures disconnecting the operators listening wires 56, 57. The closure of contact k k connects battery from battery lead 53, through contacts -41 and conductor 66 onto a" relay in the circuit of the key sets whichf connects the key set circuits onto the impulse Wires 67, 68, 167, 168 and 71 (See the above referred to application Serial N 0. 277,524, Sept. 8, 1905). The closure of contacts Is -J0 energizes the release relay B Fig. 1 the circuit being from battery lead through the contacts 7c7c 71, (72 Fig. 2, 72 Fig. 3) c, w, 73, R to ground. The relay R pulling up its armature r breaks the energizing circuit of the clutch relay R which in releasing its armatures breaks the circuit of the clutch magnet M. The tie energization of the clutch magnet allows the lever 2 to be pulled up by its retraction spring, bringing the clutch member 8 into engagement with the rotating member s which starts the primary selector switch S rotating to select the next calling subscriber. The retraction of the armature 7 completes the energizing circuit of the clutch relay R causing the secondary selector switch S to steparound in search of an idle operators trunkthe operator and circuits being as previously described. This opens the energizing circuit of the operators line relay R at c which relay releases its armae ture 1', 7* opening the circuits of the line .lamp L and busy relay R at r and r respectively. The relay R however remains energized through its locking circuit as previously described. The actuating impulses corresponding to the number of the calling subscriber and the number of the wanted subscriber now pass from the sending machine D through the operators key set circuit, conductors 67 and GS, 167 and 168 dis- 1,00 tribu ting switches S S", and into the circuits of the selectors and connectors shown in Figs. 1, 2 and 4 where they effect the desired connection..

The two sets of impulses corresponding to the numbers of the calling and called subscribers are sent simultaneously over the conductors 67-438 and 167 and 168 respectively, the former actuating the switches S, S and S" Figs. 2 and 1 and the latter actuating the switches S, l and S Figs. 2 and d.

As the circuits and operation of the two sets of switches are identical it is neccssary to describe the operation of one set only, e. g. the set which effects the connection of the calling subscriber.

Electrical impulses corresponding in number to the first digit of the calling subscriber are sent from battery over the wi e 68 Fig. 3 energizing the vertical relay R Fig. 2, the circuit being from battery through the impulse sending device Fig. 3, conductor 68, w. c, 69, w, 0 74', (74C Fig. 2) 19, 50?, 75, R", 76 to ground. At each impulse the relay R pulls up closing the '1 contacts 83 and 84, and completing the engergizing circuit of the vertical magnet V" as follows: from battery lead 78, V", 79, 80, l"

81, 82, 83, 84-, 85 to ground. The actuation of the vertical magnet V causes the shaft 8" of the switch S together with its wipers to step up to the row of contacts Whose ordinal corresponds to the first digit of the calling subscriber, and which are connected to a group of ten trunks leading to second selector switches: One impulse is now sent overthe wire67 F ig. 3 energizing the rotary relay R current flowingfrom battery through the impulse sending device Fig.3, conductor 67, w, c", 70, w 86, (86 Fig. 2) 20, x 87, R to ground. The pulling up of the relay lit closes the contacts .88, 84, thereby completing the energizing circuit ofthe relay R the energizing current being .from battery lead 89, through R, 88, 84, 85 to ground. The actuation of the relay R momentarily opens-the contacts 80, 81 and closes the contacts 81, 91. The changing of these contacts 80, 81 and 91 produces no result at present and their use will be explained later, When the relay R retracts,

the arms aflaz 00 and m" of the side'swit-ch arev movedjp the second contact. Thenio ment the switch'arm w" reaches its-second contact, current is supplied to the rotary vi.-

brating magnet] R", the actuating current being from battery lead 92, through RF, 98,;-' m to, groundfiThis magnet continues to" vibrate and e'achtime it pulls up it rotates the wipers of the switch one step. The test vwiper w. of the switch passes over thchcontacts 0 successively until it finds an idle.

trunk. As ,the wiper w? passes over. the contacts leading to busy trunks the relay R will be energized :by current from battery lead 89'through R 94,- m, 95,.release relay R1 96, w, 0"1 and to ground through the corresponding 1 first selector switch of each busy trunk by way of the multiple terminals c,-back through the release relay corresponding toll? and to ground,the

switclrarm corresponding to w of the busy select p'r switch being of course upon its third; contact. It will be observed that this circuit includesthe relay R and the test relay R andthe correspondingtest relay in the busy switch, in series. The relay B being high. wound will operate on this circuit while the other two relays will not. lVhen an idle trunk is found this test circuit is broken since the wiper of the first selector switch is no longer grounded. The

energizing circuit therefore of the relay R is broken and when it retracts, the arms as, :2 m and m of the side switch are moved to their third contacts. The movement of thearm m breaks the actuating circuit of the rotary magnet It", stopping the wipers w and 10 on the contacts 0" and c of an idle trunk leading to a second selector. Battery impulses corresponding to the sec- 7 0nd digit of the calling-subscriber are now sent along the wire 74 over the path pre- .'second positions.

viously traced, to the trunk conductor 19 and through theconnected trunk conductor 15. At each'impulse the relay R pulls up, actuating curre1-t being from battery, to

. trunk over the path already traced, thence 'and which are connected to agroup of ten trunks leading to connector switches. One impulse is again sent over the trunk conductor 20 as previously described and' thence through the switch arm 00 18, w, 0 16, z 107, R and to ground energizing the relay R which pulls up'and closes the contacts 108 and 100 thus actuating the relay R, the energizing circuit'of the latter being from battery lead .1Q1through R 108, 100 to ground. The retraction of the relay R as in the case of the first selector switch S, causes a moveintent of the arms y, y y" and 3 to their This energizes the rotary magnet R 1n precisely the samemanner as its corresponding magnet R is energized,

and the shaft 8 is now stepped around to pick outan idle trunk leading to the connector switch S The test wiper 10 passes over thecontacts a and the relay R is energized in a manner and over circuits similar to relay R until the idle trunk is found, at which time it lets go and moves the side switch arms fl/ 3 and y to their third position. The calling subscriber is now connected to a connector switch containing the contacts onto which his line is multipled, Impulses corresponding to the third digit of the calling subscriber are now sent over the trunk conductors 19, 15 and 11.

The relay R is operated closing the contacts and 111.- and energizing the vertical magnet V, the energizing circuit of the latter being from battery lead 112 through V 113, z, 114. 115, 116, 117, 110, 111 to ground.

Thereupon the spindle 8 is stepped .up to the row containing the contacts of the callmg subscribers line. One impulse 15 now sent over the connected trunks 20. 16 and 12.

This energizes the relay R" which pulls up closing the contacts 118, 111 and energizes the relay R in the same manner as relays R and R as heretofore'described. On the retraction of the latter relay the arms 2, 2 2 and 2* are moved to their second contacts the arm a cutting off the vertical magnet V and. connecting the rotary magnet R. Impulses corresponding to the fourth or last digit of the calling subscriber are now sent over the connected trunks 19,

15 and 11. These impulses actuate the'rotary magnet R, which steps the switch shaft s around bringing its wipers 'w", to into engagement with the contacts a leading to the calling subscribers line. A final single impulse is now sent over the connected trunks 20, 16' and 12. The relay R" is actuated and again closes the actuating circuit of the'relay R. It will be remembered that the switch arms 2', 2 e and 2 are now in their second position. The actuation of the relay R closes the springs 119 and 120, and should a third subscriber have been connected to the multiples 0 c* of subscriber A before the connection therewith of the wipers w w as above described, a busy test circuit would beestablished as follows: battery lead 121, release relay R 122, 123, 124, 120, 119, 125, a, 126, 10 contact 0 and its multiples and back upon the tip side of the connector trunk of the previously con nected subscriber and to ground through the tip relay of that trunk corresponding to R The energizing circuit of the release relayR being thus completed this relay is actuated and the pulling upof its armature r grounds the release magnet M which restores the connector switch S to its original position.

Assuming however that the contingency justdescribed has not occurred and the tip multiples '0 of the calling subscriber are entirely free, the test, circuit above described will not be completed, and the momentary closure of the springs 119 and 120 will therefore not affect the switch. The retraction of the armature of relay R moves the side switch arms 2, .2 2 and 2f" into their third position. The sleeve relay It is energized in series with the cut-off relay R of the calling subscribers line,

the circuit being from battery lead 128 through R, 129, 10, 130, 131, 8, a 6, 10, c, 4, R to ground. I The pulling up of the cut-oil relay R opens the locking circuit of the relay R at r and connects the calling subscribers line to the extensions leading to the contacts and c", and completes the actuating circuit of the tip relay R the cir cuit being from battery to the conductor 4' 'in the manner already traced, thench through armature 1*, line wire 2, sub-station :Lba'ck over the line wire 1.4, 3, 0 ,10 5. .2 7. 132, 133. 9, 134. R to ground. It will be seen that the circuit of the ringing relay/"R is completed on the pulling up of the sleeve relay R so far as to put the former under the control of the interrupter I. However, the interrupter is so perinanently connected with the-impulse sending device that the period included between the cessation of the last test impulse and the pulling up of the tip relay as above described, passes during the interval in which the circuit through I is broken." This protects the calling subscriber from being rung while his receiver is off the hook.

The actuation of the relay R causes it to attract its armature 1" which closes the energizing circuit of the relay B said circuit being from battery lead 128 through T 146, 147, T 1 18, R 119, 150, 151 to ground. It will be noted that the contacts 150 and 151 are closed immediately on the first vertical motion of the shaft 5' of the connector switch 8. The energization of the relay R breaks the actuating circuit of the ringing relay R by the attraction of the armature r After the relay R has pulled up it is locked, the locking circuit being from battery lead 128 through armature 1, 152, R and to ground as above traced. This establishes the clearing out circuit hereinafter described.

After the last impulse is sent over the connected trunks the distributing switches S and S Fig. 3 are restored to their normal or idle condition as follows: At the end of the cycle of impulses the relay R is momentarily energized by the closure of a pair of springs 136 on the impulse sending machine shown at D in Fig. 3, the circuit being from battery lead 42, through R, 71 through the operators key set, wire 135, springs 136, to ground. The energization of relay R causes it to attract its armature T which opens the locking circuit of the busy relay R Thereupon the armatures of relay lit fall back. The armature r disconnects battery from the busy test wire 43 leading to the secondary selector switches. The falling back of armature 1* takes the battery test off the wiper C and the armature r connects one terminal of the stepping relay R to ground. The removal of battery from the wiper C deprives the control relay R of its energizing current which releases its armature r and connects one terminal of the ster 1g relay R to battery, and as the side swl n arm :20

spring ofthe interrupter I, the circuit be-" ing from battery lead'143, through 1' 144, M 145. 52,'interrupter I to ground. The switch S continues to step around until, its

wipersengage contacts leading to an idle" pair of first selectors i. e. a pair of selectors whose side switches are not in the third position, whereupon the relay R being deprived of its ground connection, is, denergized and releases its armature 11 which opensthe circuit of the magnet M bringing the wipers of the switch S to rest on the contacts leading to the idle set of twin terminals of the called subscriber A.

first selectors. Any other 011 normal means associated with the first selectors S and S may be used instead of the sideswitch.

While the switch S is testing for an idle trunk the armature r? keeps battery con- .nected onto the wire 137 leading to the multiple contacts 0' thus establishing a busy test'whichprote'cts the switch S against any interruption while in the act of testing.

This temporary busy test, however, does not atl'ect the relay R as its circuit is open at 7*. Meanwhile the secondary distributing switch S tests for an idle primary switch and finds one in the manner previously described, the circuit of stepping magnet M "ation of connections aboved'escribed, so that at the cessation of the last test impulsethe side switches Z and Z are simultaneously moved into their third positions; If desired however, the two sets of actuating impulses may be made asynchronous in time with attendant advantages. Any convenient means may be used for this purpose, such for instance as two sending machines operating in asynchronism, and associated with each of is endin As the busy test for A is the-same as that described for A- we will assume'that A is not busy and that the receiver is on the hookat that station. When, the arm Z is moved onto its third position the relays R and R Fig, 4 are energized by current from battery lead 153 through R, 154, 210, 162, 163, 208, Z 206, w 0 204, R to ground. The relay R attracts its armatures 1, r r and connects the line wires 201-202 onto the extensions-203204.

The energization of thesleeve relay R completes the circuit of the ringing relay R? which is energized for a predeter mined time at each revolution of the interrupter I, the circuit being from battery lead 153 through armature 7' 176, 157, 1 158,

R 159 and to ground through the interrupter IKZAt each energlzationof the relay R it attracts. its armature disconnecting the switch circuit at the spring contacts 160 461511101 162163 and connecting the generator G onto the tip and sleeve sides fof the subscribers line at 164161 and 163--165. The ringing of the subscribers bell takes place therefore by current over one side of theline and back over the other.

When the subscriber answers the tip relay Rt is ctuated the circuit being from batarmature r nector circuit of subscriber A..

"position.

tery to the extension 204 in the manner already traced thence over the sleeve side of the line by way of armature W through the substation apparatus A back: upon the tip side and through r 203, a 00 205,

2 207, 161,160, 209, 166, R to ground. This happens, of course, at an interval when the interrupter I has cut off current from the ringing relay R allowing it to fall back and close the contacts 160161, and 162-463. The attraction of the armature r closes the energizing circuit of the relay B said circuit being from battery lead 153 through T 173, 174. w 166, R 169, off normal contacts 170, 171 to ground. The energization of the relay R causes the breaking of the actuating circuit of the ringing relayR by the attraction of the After the relay R has pulled up it is locked, the locking circuit being from battery lead 153 through armature 1' 172, R and to ground as above traced. The pulling up of the relay R establishes a,,.;clearing out circuit which is identical with that established in the opened at his book H and said relay releasing its armatures r and W completes the energizing circuit of the release relays B Fig. 1, and R Fig. 2 as follows: battery lead 121, Fig.1, R 122, 123, 174., 7' 175, T 2, 176, 177, 0, to, Fig. 2, 90, B, y to ground. The pulling up of the release relay R completes theenergizing circuit of the release magnet M, 179, 7' to ground. The actuation of the magnet M restores the connector con-- switch a to its normal position. The actuation of the relay R closes the springs 182, 183, which completes the energizing circuit of the release magnet M and relay R as follows: battery lead 180, M 181, 182, 183, 184, c, 10,96, R 95, w to ground. The actuation of the release magnet M restores the switch S while the actuation of the relay R closes the spring contacts 186 and 187, and thereby completing the energizing circuits of the release magnet M, and the release relay R the former circuit being from battery lead 180 through M, 185, 186, 187 to ground and the latter from battery lead 188 through R, 189, 190, 186, 187 to ground. The actuation of the release'magnet M restores the switch S to its normal R, 196 to ground and that of the latter from battery lead 89 through 193, 191, 196., 10 over the sleeve side of the trunk through the relay Ii 0 to ground. The relay R and R pull up closing the contact springs 221 and 222 which closure energizes the relays ll and R in series, the circuit beingfrom battery lead 198 Fig. 4, through R,

1343,; 200, 221, 222, 223, 224-, a as Fig. 2. 2.4 ingup of the relays R and R causes the releases of the switches S S and S in the same manner as that ust described for the release of the switches s, s and While I have shown and described the llest embodiment of my invention now known to me, it is obvious that my invention may be given many embodiments without departing in any Wise from its generic spirit. Moreover it isevident that there is a distinct method practised in the use of this apparatus 1 therefore intend to cover in the annexed claims the subject matter of the telephone system of my invention as broadly as is my legal privilege.

Having thus desc *ibecl my invention what I claim and. desire to secure by Letters Pat out is:

1. In a telephone exchange system. a pinrality of subscribers lines, a plurality of primary ii'itercommunicating links between subscribers lines converging upon a central point, and normally disconnected from the subscribers lines and from each other automatically operating connecting means and control devices at the central point foreffecting connections of said links to each other and over said links in opposite directions from the central point to subscribers lines.

2. In a telephone exchange system, a plu rality of subscribers lines, a plurality of primary intercoinmunicating links between subscribers lines converging upon a central point and normally disconnected from the subscribers lines and from each other, connecting" means and control devices at the central point for etl'ectine' connections of said links to each other andorcr said links in opposite directions zl'roin the central point to subscribers lines; and means auxiliary to said primary links wl'iorehy a calling subscriber may transmit a call for a connection to the said central point.

3. In a telephone exchange system a pluw, 226, :0 to ground. Thus, the pu1l- I rality of subscribers lines a plurality of primary iuterccznn'iunicating linlcs between subscribers lines converging upon a central point, and normally isconnectcd from the subscribers lines and from each o. connective and controlling means at the central point for effecting connections of said links to each other and over said links in oppo ite directions from the central point to subscribers lines, and seondary links between the subscribers lines and the central point over which a calling subscriber may communicate a call a desired connection be tween his own line and another over said primary links.

4. In a telephone exchange system, plurality of subscribers lines, a plurality of primary connector linlishaving automatic connector switches at their line ends and containing: bank contacts of-niultipled line terminals of saiel lines, cross over trunks at their inner ends for automatically interconnecting the same, an operators hey seta central stationasscciated with said trunks and adapted to initiate and elli'ect connectious in oppo e directions by Way of said connector liincs to calling and callec. lines respectively, and secondary automatic connective links between the snbscriloers' lines and the operators lcey set whereby the subscrihers may communicate calls :lior clesiretl and called lines respectively, and auxiliary links indeiendent or the aforementioned connection extending; from the subscribers lines to the central station whereby the suoscriher may initiate a call to the central station for the aiorcnientioi'ieil connc ion. 6. In a telephone exchange system a plurality of subscribers lines to he interconnected, a plurality of connector linh's con verging upon a central point for interconnecting them, but normally disconnected thererroni and from each other, a plurality of cross over trunks for interconnecting the.

linhs said trunlcs each having a first selector switch at each enrl containing multiples of the inner terminals of saicl connector links. illlil said connector links terminating in connector switches contain hanl: terminals of the subscribers lines. iinpulse'transinitting moans associated with said trunks and adapted to transmit separate sets of selectire impulses over said cross over trunks. from a central point in opposite d rections simultaneously to select and connect two suhscrihcis lines for talking through said cross over trunks.

7. In a telephone exchange system, 'a plurality of subscribers lines to be interconnccted, a )lurality o'l"co mector links concalled linesrespectirely.

. so i ranged connect ng trunks harm; selector switches permanently connected at each end.

ergring upona central point for interconnecting them, hutnormally disconnected therefrom and from each other, a plurality of cross over trunksfor interconnecting the links, said trunks each having a first selector switch at each end and containing multiples of inner tern iinals of said connector links, and said connector links terminating in connector switches containing hank ter-x ininals of the subscribers lines, impulse transmitt ng means separately connected to opposite endsot said cross over trunks lor the-transmission of separate sets of actuating impulses to the trunk, -\\'hcreliythe sets of impulses .are transmitted one from one end to the trunk and one from the I'other to sel'iarately ctl'ect connection of the trunks through the connector links to calling and 8. In a telephone exchange system. a plurality of 'suliscrihers lines to lie interconnected, a plurality of .symmetrically arand an impulse sending de ice connected with: said trunks for transmitting impulses to cause said switches to elicit directly controlled connections oycr opposite ends of the same to calling and called lines respectively.

9. In a telephone exchange s \'stein,a plurality oti--siil;sci'ihers lines to he interconnected. 'a pluralityot' symmetricallyv arranged connecting trunks ha ing selectoi" switches permanently connected at each eml containing hank terminal connecting contarts. and an impulsesending device-connected with said trunks for trai'isinitting ii'niulscs to. elicit connections over opposite endsol' the same to'calline; and called lines, respectively, and means in the trunk separating the'sets of impulses from each other.

10f In a telephone exchange system. a. plural ty ot snhscrihers" hues and a plurality oi connector link circ nts for intercom necting the same tliesaidcircuits tei-minat-- me" n auto nat'nconnector sw tches containiqg multiple terminals of the lines, actuatingand releasemagnets tor saidconnector switches, a battery supply relay energized when the fsuhscrihefs receiyer is rumored from. its hook, means partially closing a circuit for the release magnet upon theencrgizatmn of said supply relay, and means com' 'ileting said releasen'iagn'et circuit upon deenerglzationof said supply relay.

11.- lira-telephone exchange system, a phi rality of Subscribers lines, and a plurality the connector .lin'k of connector link circuits for intereonm-ciin;: the same. the said circuits terminating in automatic connector switches containing multiple terminals of the lines. actuating and. release magnets 'l'or said connector switches. means acting upon removal ol the line receiver from the hook to partially close the relcasecircnit and means actin e upon the replacement of the receiver on the hook "to complete the closure of said release circuit.

12.- In a telephone exchange system. a plu rality ol snhscriheis lilies. and a'pair of associated link circuits for interconncct'ing the same. -ach link terminating in a connecto'r switch containing multiple terminals of the vseveral lilies. actuating and release magnets to! each switch. a test circuit adapted to he closed \\'hen the wanted line is found hits to energize said release mag not, a battery supply relay through which the testing circuit is closed. and means \herch when the wanted 'line is found linsy,.the release inae'netx-ofthe testing. switch will send a hack release impulse over the release circuitot the associated connector linlt'. i v v) i I 1 y I o. In av telephone.exchange system, a plurality ol suhscrihers' lines, a plurality of connector link circuits for interconnecting thcin converging upon a central point, said link circuits litlllfl normally disconnected li'om said lines and trom each other, automatic, connector switches iii said links for cll'ccting connection with said lines, actuatine and releasing means for the same, means for interconnecting the inner ends of the links, a *release circuit established simultaneously with any connection 'lroin the central point to a suliscrihers line, actuating and release magnets for the switches of the links a test circuit for each connector, and means associated with said circuit whereby vwhen the wanted lines test hi'isy, the hack releaseimpulse is'scn't o ersaid release-circuitenergizine' in order the release magnets 'ol' the links. and additional nieans'asso the same wherehy a release originatedat one end of a connection is .transn'iitted backward to ;an intermediate point, and then foi ward to the opposite end of the connection and thence hack to the central point.

.15. In -a telephone eychangesyst erna. plurality of lines, a symmetrically arranged link for interconnecting the same provided with selector switches at each end'through which connection may be efi'ected with call ing and called lines, means conductively separating but inductively uniting the opposite ends of said link, actuating and release magnets for said switches, means for originating and transmitting actuating and release impulsesto the said'magnets and a transfer connection for release impulses from one end of said link to the other.

16. In a telephone exchange system, a plurality of lines, link circuits and automatic switches for interconnecting the same, actuating and release magnets for the switches, a special. release conductor associated with certain of said links and adapted-to eifect operation of said release magnets from one end of an established connection to an intermediate point, and a transfer conncction at said intermediate .point whereby a release 1mpulse is transferred from said special release conductor to'and transmitted. forward over the link conductors themselves to eii'ect the release of the opposite end of the connection.

17. In a telephone exchange system, a

plurality of lines, a plurality of connector link circuits having automatic switches for eil'ecting connection with the same, actuating and release magnets for said switches, a second link having an automatic switch adapted to connect with any oneof a plurality of said connector links, means whereby a forward release'impulse may be sent over said circuit to energize said releasemagnet, means in said connector link responsive to said release impulse to momentarily energize .saidrelease magnet over a release circuit extending through the said. second link and including a release magnet of said second link, and means operative upon energization of the connector release magnet to lock said bearing a determinate time relation to the operation of said sending machine in transmitting test impulses onto the links.

19. In a telephone exchange system, a plurality of subscribers lines, and a plurality of connector link circuits having automatic switches for connecting them, actuat ing magnets for said automatic switches, a testing means, a rmglng relay, :1 step control device for the switches for directively governing the stepping of the switch to desired positions,means to send a testing impulse at the close of the stepping of the switch, a circuit for said ringing relay, and means separate from the aforesaid means for testing, for closing the ringing circuit and bean ing a determinate time relation to the sending of said testing impulse.

20. In a telephone exchange system, a plurality of subscribers lines, a plu 'ality of connector links having automatic switches for connecting the same, actuating means for the switches. and testing means for the lines and a ringing relay associated with each of said connector links, a sending machine associated with the links and adapted to transmit actuating and testing impulses thereoi'er to the actuating and testing means respectively, and a circuit for the ringing relay opened and rloscd by a commutator having a determinate time relation as respects the sending of the test impulses, said relation being such that the circuit of the ringing relay of any connector link is not closed until after the final test impulse has been sent.

21. Ina telephone exchange system, a plu rality of subscribers lines to be interconnected, and a plurality of double ended connector links having automatic selector switches through which connection may be effected between calling and called lines, means associated with said links for simultaneously transmitting selected impulses of different order for each of 'said switches whereby two subscribers may be connected through the links.

22. In a telephone exchange system a unitary connective link having an automatic switch at each end through which directively controlled selection of calling and called lines may respectively be made, and means conductively separating but inductively uniting said switches,

23. In a telephone exchange systema uni tary connective link having an automatic switch at each end through which directively controlled selection of calling and called lines may respectively be made.

24. In an automatic telephone exchange and active to select and hold in readiness an idle connective link, and a secondary distributing switch associated with each operators position and adapted to pickout and hold in readiness a primary distributing switch which has selected and is holding in readiness an idle link.

25. In a telephone exchange system, a plurality of subscribers lincsha plurality of double headed connective links. symmetriwally arranged automatic switches at each enih said lines being accessible for calls through the said connective links only, a plurality of operators positions haying sending machines adapted to transnnt selective .2111 idlclink and a secondary distributing switch associated with each operators key set and contaiuiir; multipled extension-tel minals ol the primary distributing switches. and each adapted to select and hold in r *adiness :1 primary distrihuting switch whose terminals have connected with'an idle link.-

26. in a telephone exchange system. a plurality of lines. a plurality of link circuits ontainingautomatic switches adaptedito interconnect the same an ope'rato1"s key set ha ing associated therewith means for trans mitting selective impulses over said links, a distributing switch adapted to select and hold in readiness an idle link, a'n'dthrough which the selectiveimpulses are transmitted from the key set to the selected link, a path auxiliary to the aforesaidlinks oyer which a subscriber may connnunicat a call to" a given connection, and a busy relayassociated with sald distributing switch and active upon the transmission oi a call over said auxiliary path to render the said selected idle -link busy.

27. In a telephone exchange system, a plu rahty of hues to be interconnected.a. plu rality of link circuits containing automatic switches adapted tointercminect the same and including lirst selector trunks, an operlators key set having associated therewith means for transmitting selective impulses over said links, fl tllfitl'llflltlllg switch adapted to select andhold in readiness .anidle first selector trunk and through which the selecti\'e impulses are transmitted from the key set to the selected link. a path auxiliary to the aforesaid links oyer whi'clia subscriber may ctnnmunieate a call for a given connee' tion, a busy relay associated with said distributing switch and active upon the transnission of a call over said'auxiliary path to render the saidiselected idle link busy, means i disconnecting said auxiliary path upon the commeneement of thetransmission impulses,

' and means whereby said busy 'relay locks itseltuntll-thetransmission oi said impulses ing is completed. i a

28. In a telephone exchange system, a phi rality' of subscribers lines, a plurality of double, headed primary connective links haysymmetriea'illy arranged automatic switches through which the lines are accessi' .ble, a plurality of operators key sets having at each end of the trunks, a distributing switch adapted to pick out and hold an idle trunk. an auxiliary automatic connective circuit adapted to connect the subscribers with the operators key sets independently of the aforesaid primary links and adapted to pick out and hold in readiness an idle key set tor any incoming'call, means whereby the operators set and the selected idle trunk are rendered busy upon the initiation of acall over said auxiliary path, means releasingthe. auxiliary path for the communication of other calls upon the transmission of impulses to the selective trunk, and mains whereby the operators set and the associated distributing switch are released and again rendered idle upon the complete, transmission of the actuating impulses.

In a'telephone exchange system, a plurality of subscribers lines, a plurality of. doublaheaded primary connective trunks haying symmetrically a'r 'anged automatic switches through which the lines :IIGRCCGSSlconnective circuit adapted 'to' connect the subscribers with the operators key sets in-. dependently of the aforesaid prima ry links and adapted to pick out and hold in readiness an idle key set for any incoming call','means whcrehy the, operators set and the selected idle trunk are rendered busy upon the initiation of'a 'all over said auxillary path, means releasing the auxiliary path for the commuuicatioi'i of other calls upon the transmission of impulses to the selective trunk.

30. In a telephone exchange system, a plurality of subscribers lines, a plurality of double headed primary connective trunks having symmetrically arranged automatic switches through which the lines are accessible a plurality of operators key sets having impulse transmitting means adaptedsimultaneously to actuate the automatic switches at each end of the'trunks, a diStributing switch adaptedto pick out and hold an idle trunk an auxiliary automatic con .nective circuit adapted to connect the subscribers with the operators key sets independently of the aforesaid primary links and adapted to pick out and hold in readiness an idle key set for any incoming call,. means whereby the operators set and the selected idle trunk are sii'nultaneously rendered busy upon the initiation of a call over said auxiliary path, and means whereby the operators set and the associated distributmg switch are released and again rendered loll upon the complete tiansinission of the actuating impulses.

e 1, In a telephone exchange swstein, :i plurulity of subscribers lines to be interconnectecl, "iliuslity of double enclcol connective trun lia sing symmetrically arranged automatic SQlQCtOl switches at each end through which connection may he made simultaneously with two cliil'crent lines, and a double key hoard operators set associated therewith and adapted sin'uiltaneously to send. a set of actuating impulses to each end of said trunk whereby connection may he made between the two lines through saicl trunk, anal means in the trunk for confining the respective sets of impulses each to its own end of the trunk.

In a telephone exchange system. a plucality of subscribers lines, a plurality of connector trunks adapted to interconnect the same and provided with automatic switches therefor, a plurality of operators key sets adapted to he associated each with any one of said connector trunks, primary distributing; switches each auspice zuitoniatically to selectv hold in readiness an idle connector trunk, a secondary distributing switch associated with each operators st and adapted to select and holcl in readiness a primary istrihuting switch which holds in readiness idle trunk, means opeiutive upon the completion any set of actuating impulses sent through the primary (listrihuting switch to sturt the same in search of another irllc trunk, and means rendering the terminals of saidv primary distributing switch busy (lining its testing operation whereby said secondary distributing switch is caused. to u s from its terminals and.

select another idle primary distributing switch.

In a telephone exchange system, a plurality of lines, connective links a ml auto inaticswitches for interconnecting the same, p im-a1." distributing switch containing; t nnuls for selection of and connection with an idle link, independently of line connection with said link, saicl switch after testing for aiul selecting an idle link, acla eil to hold the same in readiness for call over a line, and means P sine! clisti'iluiting switch is ren- U ml liusy and will noticspoiul to incoin ing culls (luring); its operation of testing for an idle link.

3% In a telephone exchange system, plurality of lines to he intei'connec plurality of connector i'llslllifl ha in an sntoinu ic switch st each end :ulaptecl to interconnect "the same, a plurality oi lacy adapted to transmit actuating impulses to said trunk to up said switclies'to interconnect the sa -l a p'imarv' clistrihuting switch which said operators set may be connected with trunk, an oil-normal means associated with one of the switches in each trunk, an zzctuating magnet for said distributing switch, and a control circuit for the same adapted to be closed by said oil-normal .means upon the completion of the switch actuation by impulses sent through said distributing switch, whereby said distributing switch is thereafter caused to step fob ward to select another idle trunk.

in a telephone exchange system, a plurality of subscribers lines, and a plurality oi connector trunks adapted to interconnect the same, a plurality of operators key sets adapted. each to transmit selective i111- pulscs over said trunks when connected thereto, a primary distributing switch adapted to select and hold in readiness an idle trunk, a secondarydistributing switch adapted to select and hold in readiness a primary distributing switch which has so .lecteil an idle trunk, means controlled from the connected. trunks to start the primary distributing switches toselect idle trunks upon the complete transmission of any set of impulses, and a starting circuit for the secondary distributing switch controlled jointly by the transmitting device of the operatofis set and the starting device of the primary distributing swit-c 35. in a telephone exchange system, a plurality of subscribers lines, a plurality oi automatic connective links for interconnecting them, an operators key set for transmitting selective impulses over the links, a ilistrilnitin g switch between the key set and illt) links through which the impulses are so 1'; to the links, s: id switch. being aclaptecl to pick out and connect to said operators set an idle link, an actuating magnet for said switch and a control circui for said magnet controlled jointly by oil-normal means in said links and said operators key set.

37. in a telephone exchange system, a plurality of lines, a pluriility of links con 'taining automatic switches for interconnecting them, a dish-uniting switch adapted to select and llOlil in readiness for use an idle link, a central oliice sending device transmitting inipulr s to said selected link, actuating nun-ms for Slllll distributing switch, and a llll'l't'l l circuit for said actuating means the closure ofwhich is determined by said sending iilcvice.

38, in a telcpl'ione exchange system, a plurality of connective links having automatic switches for chie -tin connections, a pi'iinu y oistributlng switch adapted to select ancl hol-zl in i'eacliness for use an idle link, a secondary switch adapted to select and hold in readiness for use a primary switch which has selected an idle link.

means l'or ell'eeting ronneetions by way of the st-lerted idle links. a release for the primary su'iteln and a release for the seeondary su'iteh elleeti e upoili the release ot'the said primary sy iteh.

1 in a telephone exehange s item,

pluralit ot primar ronnet't'iVe li uk lia ing automatie switrhes. subseribers lines to be interronm-rt'eil t|iereb \'.'a sending deyire intermediate railing and rall ed subseribers lilies adapted to ell'ert eonnertion byway ofi said links between ralling aml railed sublit) ii links seribers lines. automatie suitehes through whieh said sending deriee is automatieally assoeiated' with idle links when itsell idle. seeoml'ary links adapted to' antomatirally eonneet subscribers with the operators set, a busy relay responsive to said eonneetion to render the said"operators setand switches all busy to other. eouueetions. and a loeking eireuit for said relay t'ontl'olled by the operatons sending maehine. whereby the busy test is not'remoyed until after the ronnee tiou hasbeen made. i v p -"l().' in a telephone exehange system. a pinrality of 'eonneeti elinks haying aiitomatie s\\' it 'h es. 'a distributing switel't adapted to seleet and hold in readiness an idle link. a

- tll(llllf tuat'llilie adapted to send se'leetive iuu ulses. to said links through said distributn'tg su'iteh. a busy relay:rendering said.

distributing switr h and sending maehine busy during thev tune impulses are being sent. aml a lot-king eireuit l'or said relay eontrolled by said sending tn'aehiue \\'hereb diate the eallin'g and ealled subseribers stalions tor the transmission Ui'stltt'ih-t impulsesin opposite direetions to buildup a eonneeti e eirruih an :iuxiliary eommunieating path by \rhieh the subserila-rs may 'eonununieate with an operators position iudependeutly of the eonu'eeti'ye links. a-.eall" signal 'at said operator s position operated when the subseriber is eouneeted with said position over said path. and a deyiee-reudering said operatons position busy to other ealls upon the rta'eption-ol' said signali" 1;. in a telephone exehange system.a plurality of subscribers lines. a plurality ol' tit) doublehetnltal eo'nueetor links ha ing automat ie switches at aelt end through \\'llit'l\ (,(Hltltt'tilOIlH'1112i) be made to railing and ealled lines respeetiyely. an operator s transmitting de\'ie'e assoeiated with said trunks.

and adapted to transmit the number of a ealhng subscriber to one end of said trunks,

and the n'umberot a ealled subscriber to the other end of said trunks. and secondary links beti een'the subseribers' lines and the positions oyer \\'lli('ll a subscriber may t ansinit a tall for a eonnection between his myn line and any other by way of said primary links. i I

$3. In a telephone exchange system, a pinrali'ty ot 'subseribersdines. a plurality of eonneetor links ha ing automatic switches for ii'itereonntwting them. means at a eentral point lllttl'lllttlltltt the subseribers lines for transmitting aetuating impulses over said links to intereonneet said lines in pairs,

means at said point for registeringineounng ealls-t'or transun sion by nnpulses,

and means auxiliary to said ("tilttltttfil' links whereorer a eallmg;subseriher may t'ansnut-ealls for registration on said transmit ting devices rality ol subseriherslines. a plurality of primary eonneetor links ha ing automatic switehes l'or intereonnet-ting them. a plurality of operators positions ha ing impulse transmitting.devices adapted to be asso eiated with-said links to eti'eet eonneetions between the lines. a plurality oti auxiliary seeondary links eontaining automatic suitehes adapted to etleet. connections bet\\"een subserilwrs and the ope 'ators' positions. operators telephonestits. an opera-.

tor's listening key adapted when pressed to eonueet and loek said listening'set on one of said auxiliary paths. a starting key for the impulse transmitting derive. and means eontrolledby said starting key l'or releasing said auxiliary path from the telephone set.

1 .15. In a teleplione exehange systeuna plu' ltllli) ol' subsel'lbers' llllts.

plurality of rimary ronneetor link eireui s'l a lug autoniatuswitehes lor intereonneetmg the same.

a plurality ol'operators' key sets ha ring imv pulse transmitting de iees adapted to trans- In a telephone exchange system. a plumil impulses o er'said links when eonneeted v thereto and to ell'eet' eonneetion between said lines in pairs. a pluralit ol seeondary eonneetor link-s eoniprising primary and seeondary selt-a-tor '.s\\'itehes adapted respeetiyely to seleet ralling lines. and idle key sets.- and means operative upon the transmission. of

unpulses In response to anyflrall to relea e said primary elert'or su'iteli'es otjer said set' mulatypaths t'rom eonheetion \\'1ill 2\ll \'l l1(.

and said sei-oudary seleetor s\\'itehes ,i'rour eonneetion with the tlion busy operator's key et.

H3. ln a telephone exehange s \'ste1.i.a plu' rality, ol"subseribers lines. a plurality of rimary toitltt't'itil" links eontaining gainmatie switehes aml adapted to-ell'ert eonneetion between lines in pairs. a plurality of operators positions having impulse transmitting devices adapted to transmit selective impulses to the links when connected thereto and effect connections between the same, a pluralityot separate secondary links contaii'iing primary and secondary selectors adapted respectively to ellect connection with calling lines and idle operators positions, said switches being connected permanently in series, a locking relay for the primar selector switch retaining the same in connection with the calling lines, means operable upon the transn'iission of selective impulses from the operators position to release said primary selector switch, and means operable by said Holding means upon its release for efiecting the release of the second ary selector switches from the connected operators position.

4". In a telephone exchange system, a plu rality of subscribers lines, a plurality of connective links for interconnecting them, a plurality'of operators sets associated with the connective links and adapted when connected therewith to transmit impulses thereover to efi'ectconnections between the lines in pairs, primary distributing switches containing non-multiple bank contacts of a plurality of connective trunks adapted to pick out and hold an idle link, and a secondary distributing switch containing multipled terminal contacts of the primary distribut ing switches, one of the secondary distributing switches being associated with each operators set, and adapted to pick out and hold a primary distributing switch connected to an idle link. 48. In a telephone exchange system, a plurality of subscribers lines, a plurality of primary connector links having automatic switches adapted to eliect connection between said lines in pairs, an operators set adapted to transmit selective impulses over said links to effect said connections, a distributing switch associated with each ks set and adapted to pick out and hold an idle link over which to transmit said selective impulses, a secondary selector switch and secondary connective circui'tassociated therewith over which a subscriber may communicate a call to an operators set, and a busy relay operative upon communication of a. call to make the operators set and the link held by the distributing switch busy to other calls.

49. In a telephone exchange system, a plurality of lines to be interconnected, and a plurality of automatic connective links adapted to effect said interconnection, said links having primary selectors at one end, and secondary selectors at the other, the said primary selectors being normally active to select a calling line, and said secondary selector normally holding another line in tiple terminals of the lines,

readiness for connection thereto through the primary selectorw 50. In a telephone exchange system, a plurality of lines, a plurality of automatic connective links for interconnecting the sanie,

each connective circuit having at one end a primary selector switch containing multiple terminals of the lines, and at the other end a secondary switch containing other multiple terminals of the lines, said switches having their movable terminals normally connected together, means whereby the primary switch is normally active to select a calling line of its group, and means whereiy the secondary switch normally holds ready for connection with the selected line a pro-selected line of its group.

51. In a telephone exchange system, a plurality of lines to be interconnected, a plurality of automatic connective links for effecting said connection, each complete connective circuit having at one end a primary selector switch containing multiple terminals of the lines and at the other end a secondary switch containing other mulsaid switches having their movable terminals normally connected together, means whereby said primary switch'is normally active to select a calling line of its group, means whereby the secondary selector normally holds ready for connection with the selected line a pre selected line of its group, and means whereby release of the primary switch effects operation of the secondary switch to presele't another line of its group for a succeeding connection.

52. In a system of communication between subscribers and operators, a plurality of automatic connective links adapted to connect calling subscribers lines'with positions of idle operators and comprising each a primary selector atone end adapted to connect with a calling subscribers line and a secondary selector at the other end adapted to pre-'.

select an idle operators position, means controlled by the operator for releasing the primary selector switch, and means controlled upon the release of the primary selector switch for initiating actuation of the secondary switch to select another idle operator.

In a system of intercommunication between subscribers and operators, a plurality of automatic connective links containingr each a primaiy'selector adapted to connect with calling subscribers lines and a secondary selector adapted to connect with idle operators sets, means operative upon connection of a calling subsoribers line with an idle operators set to render the said operators set busy to secondary selectors disconnected from calhng subscribers lines,

and means under control of the operator for 1 stroying the established busy. test.

p In a system. of lintercomunmication between subscribers and operators. a plurality of automatic connective circuits comswitch,

prising each a permanently connected prism inary selector switch and secondary selector said primary switch containing multiple terminals of the lines and said secondary switch containing,multiple cir- .cuit terminals of operatorssets, means whereby the secondary switch .is operative to hold in readiness an idle operatmYs key set, and means whereby the primary switch is operated to connect the same with v the calling line. I

In a telephone exchange system, a plurality of subscribers lines tobe interconnected, a. plurality of primary double ended connective trunks ha ing symmetrically arranged automatic selector switches at each endthrongh \\'hich connection may be made simultaneously with twodilterent lines, and a dbnble operator-s sending device associated therewith and adapted simultaneously to send actuating impulses to'the opposite ends of said trunk whereby connection may be made between the'two lines through said trunk.. 56. A telephone. exchange system int-ind ing'telephone lines; a plurality. of link connectors each provided with i operator controlled means at both ends t r zoii icctthe same with lines; .and operatons selector mechanism for selecting link connectors that aretree for selection. said operator controlled means performing theirline joiningfunction indcpeiulcntly of said selector mechanism, there beingauton'ratically operate'dswitching mechanism for connecting the link. connectors with called lines.

57. A telephone exchange system including telephone lines; a plurality of link connectors each pirovidmlfwith operator controlled means at botlrends to connect the same with line. and operator-"s selector mechanism for selecting, link connectors that are tree for selection, said operator controlled ymeans pcrl'ormmg their. line" joining function independently of said se lector mechanism, there. being automatically operated switching mechanism for connecting the link connectors with calling and all lines.

58. A telephone exchange system including, telephon. lines extending to an exchange having a 'i-aoalityol opcrators positions l nk connectors common to the operators positions and each provided with operator controlled means at both ends to connect the same with lines; and olmrators link con' nectm selectors for selecting link connectors that are free, tor select on, sard operator connecting the link connectors with callinglines.

ingtelephone lines extending to an exchange haying a'plurality ol inicrators' positions: link connectors common to the operators position and each provided with operator controlled means at both ends to connect the same with lines: .and "opwralorsi link con nector selectors l'or selecting link connectors that are free for selection. said operator controlled means performing their line'joining function indcpendently ol said link connector selectors. there being automatically operated switching mechanism for connecting thc li'nk connectors with called lines.

(ill; A telephone exchange system including telephone lines extending to an exchange having a plurality of operators positions: link connectors connnon tothe operators po sitions and each provided with operator controlled means at both ends to connect the same with lines: and opcrators' link connector selectors for selecting link connectors that are. Free for selection. said operator controlled means performing their line joining Function independently of said link con nect0r selectors, there. being automatically scriber may communicate his order to an op orator over -said. control trunk, releasingncans for said control trunk, additional /ineans whereby an operator may directiyely control the operation of certain of said switches over a trunk separate lrom and; after the release'o'l said control trunk.

59. tclcplume exchange system inclnd (32. In a telephone exchange. system in-' cluding telephone llllth 'jllltfllllilllli switches for intcrcon-necting said lines, an opcratoi"s position and order trunks extending thereto, of means for automatically connecting with calling lines over saidordcr trunks. service trunks extending. to certain ot said auto- 'matic switches, automatic means associateit with said position for causing selection oli. certain of said automatic switchcs,- additional antomaticmeans associated with said oper'ators position for causing the automatic switches so selected to interconnect said lines corresponding to the communication" re .ceived .oversaid order trunks. (33. In a telephone. exchange system including telephone lines, automatic switchcs' 

